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Date: Tue, 14 Nov 2006 14:02:21 -0800 (PST)
From: Jeff Frost <jeff@frostconsultingllc.com>
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On Tue, 14 Nov 2006, Bruce Momjian wrote:

> Your description was too detailed, but I took some of your concepts:
>
>  <para>
>   In clustering, each server can accept write requests, and these
>   write requests are broadcast from the original server to all
>   other servers before each transaction commits.  Heavy write
>   activity can cause excessive locking, leading to poor performance.
>   In fact, write performance is often worse than that of a single
>   server.  Read requests can be sent to any server.  Clustering
>   is best for mostly read workloads, though its big advantage is
>   that any server can accept write requests --- there is no need
>   to partition workloads between read/write and read-only servers.
>  </para>
>
>  <para>
>   Clustering is implemented by <productname>Oracle</> in their
>   <productname><acronym>RAC</></> product.  <productname>PostgreSQL</>
>   does not offer this type of load balancing, though
>   <productname>PostgreSQL</> two-phase commit (<xref
>   linkend="sql-prepare-transaction-title"> and <xref linkend=
>   "sql-commit-prepared-title">) can be used to implement this in
>   application code or middleware.
>  </para>

Bruce,

Continuent's uni/cluster middleware product implements this type of 
clustering/load balancing.  Perhaps it warrants a mention?  Not sure how far 
we want to get into listing external products.


-- 
Jeff Frost, Owner 	<jeff@frostconsultingllc.com>
Frost Consulting, LLC 	http://www.frostconsultingllc.com/
Phone: 650-780-7908	FAX: 650-649-1954